Problem
Given an array of positive integers nums and a positive integer target, return **the *minimal length* of a subarray whose sum is greater than or equal to** target. If there is no such subarray, return 0 instead.
Example 1:
Input: target = 7, nums = [2,3,1,2,4,3]
Output: 2
Explanation: The subarray [4,3] has the minimal length under the problem constraint.
Example 2:
Input: target = 4, nums = [1,4,4]
Output: 1
Example 3:
Input: target = 11, nums = [1,1,1,1,1,1,1,1]
Output: 0
Constraints:
1 <= target <= 1091 <= nums.length <= 1051 <= nums[i] <= 104
Follow up: If you have figured out the O(n) solution, try coding another solution of which the time complexity is O(n log(n)).
Solution
/**
* @param {number} target
* @param {number[]} nums
* @return {number}
*/
var minSubArrayLen = function(target, nums) {
var left = 0;
var right = 0;
var sum = nums[0];
var min = Number.MAX_SAFE_INTEGER;
while (right < nums.length && left <= right) {
if (sum < target) {
right++;
sum += nums[right];
} else {
min = Math.min(min, right - left + 1);
sum -= nums[left];
left++;
}
}
return min === Number.MAX_SAFE_INTEGER ? 0 : min;
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(1).